Plasma display device drive identifies signal format of the input video signal to select previously determined control information to drive the display

ABSTRACT

A plasma display device and a method of driving a plasma display which are capable of performing suitable display control in response to the signal format of an input signal are provided. Either a television signal or a graphic signal is inputted as the input signal. A signal format identification circuit identifies whether the signal format of the input signal is the television signal or the graphic signal. A mode-by-mode control signal generating portion determines the driving sequence of a driving circuit in response to the identified signal format to perform the driving control of the driving circuit. Then, a display panel is driven in response to the signal format of the input signal to display an image.

This application is a continuation of application Ser. No. 09/046,135,filed on Mar. 23, 1998, the entire contents of which are herebyincorporated by reference and for which priority is claimed under 35U.S.C. §120; and this application claims priority of Application No.9-081039 filed in JAPAN on Mar. 31, 1997 under 35 U.S.C. §119.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma display device which controlssignal processing in response to the signal format of an input signal.

2. Description of the Background Art

A plasma display panel (PDP) has been hithertofore known as one of theflat panel displays and received much attention as an alternative to acathode ray tube (CRT).

Displaying an input video signal on a PDP requires the conversion of thevideo signal into pixel-by-pixel digital image data. Each pixelcorresponds to a discharge cell which is a unit of discharge in the PDP.Gradation control at each discharge cell is such that a field is dividedinto subfields based on the number of gradation levels and luminescenceor non-luminescence in each of the subfields is controlled. For example,if digital data indicative of a gradation level at each discharge cellis 6-bit digital data (64-level gradation), one field is divided intosix subfields, and luminescence or non-luminescence in each of the sixsubfields is controlled depending on whether each bit is “1” or “0”. Theluminance at each discharge cell corresponds to the digital data bysetting the ratio of the number of sustain pulses in each of thesubfields to 2⁵ (MSB) to 2⁰ (LSB). Thus, the increase in the number ofsubfields increases the number of gradation levels to achieve smoothdisplay having improved gradation properties.

The luminescence or non-luminescence at each discharge cell iscontrolled in a manner described below. First, a priming pulse isapplied to force a discharge to be produced at all discharge cells andto erase wall charges. Then, a scan pulse is applied to a scan electrodeand an address pulse is selectively applied to an address electrodedepending on display data to control whether to provide wall charges ornot. This determines whether to cause luminescence at the associateddischarge cell using a subsequent sustain pulse or not. At this time,reliable luminescence and enhanced display stability are achieved byincreasing the pulse width of the scan pulse to prolong write time forproviding the wall charges.

The division of one field into subfields for display control at eachdischarge cell as above described presents a problem in that a pseudocontour is produced when a moving picture is displayed. Specifically, anobserver that follows a moving picture with his or her eyes finds thepseudo contour produced in a section of an image where the gradationshould change smoothly. To prevent this, it has been proposed tosubdivide a predetermined number of subfields to alleviate the movingpicture pseudo contour.

The above described control accomplishes multi-level gradation display,high-luminance display, stable luminescence, prevention of movingpicture pseudo contours and the like in the PDP image display.

The time required for one field is a fixed value determined by an inputsignal dependent upon a signalling system such as NTSC, PAL, and VGA,and is generally 16 to 20 msec. The above described control must beperformed within this limited length of time. Unfortunately, time isinsufficient for the control that satisfies overall performance.Specifically, the increase in the number of subfields, the elongation ofthe write time, and the subdivision of the subfields require accordinglylonger time for one-field display, resulting in the insufficientexecution of the above described control.

Further, signals are classified depending on the signal format, forexample, into an interlaced scanning signal (referred to hereinafter asan “interlace signal”) and a non-interlaced scanning signal (referred tohereinafter as a “non-interlace signal”). The PDP which fundamentallyuses the non-interlace signals for display is required to perform aninterpolation process on the interlace signals to convert the interlacesignals into the non-interlace signals. The interpolation processincludes, for example, producing an intermediate horizontal line signalfrom two horizontal line sign upper and a lower. Disclosed in JapanesePatent Application Laid-Open No. P05-216433A (1993) is a simple processfor driving the PDP so that one field of the interlace signal isdisplayed in a pair of lines, thereby to display the interlace signal,without using the conversion into the non-interlace signal by signalprocessing. This technique enables a pair of lines to be written at atime, reducing the time required for the write operation by half, butrenders a displayed image rough on the whole since the same signal isdisplayed in the pair of lines. The use of this drive process requiresthe PDP to be used specifically for an interlace signal input and tofail to display the non-interlace signals such as VGA.

The time required for one field differs depending on the signal formatof the input signal such as an NTSC system, a PAL system, VGA, and XGA.The level of the luminance in the plasma display is generallyproportional to the frequency of the sustain pulse. Thus, changes invertical synchronization frequency change the frequency of the sustainpulse depending on the signal format of the input signal, therebychanging the maximum luminance. frequency change the frequency of thesustain pulse depending on the signal format of the input signal,thereby changing a maximum luminance.

The amount of power consumption in the plasma display is proportional tothe product of an APL (Average Picture Level) and the luminance. The APLis defined to mean a numerical value obtained by averaging the gradationlevels (%) of all cells. For instance, the APL is 0% if black isdisplayed on the full screen, and is 100% if the highest gradation levelof white is displayed on the full screen. The APL of a typical image issaid to be an average of about 30 to 40%.

Thus, the increase in the frequency of the sustain pulse for higherluminance is not a problem for a typical screen but results in theincrease in power consumption for a special screen, for example, ascreen on which white is fully displayed. Countermeasures against thisproblem include APC (Automatic Power Control) which controls theluminance depending on the APL to suppress the power consumption at afixed level or lower. This method is capable of suppressing maximumpower consumption at a fixed level or lower on a typical screen whilemaintaining a high luminance, but presents another problem when agraphic signal (VGA, XGA and the like) from a personal computer isdisplayed. When a fixed screen (still picture) having a low APL isdisplayed in the form of a graphic signal, particular cells thatcontinue high-luminance display are deteriorated, resulting in burning(image sticking on the screen).

Furthermore, in the PDP, a priming discharge (discharge at all cells)based on a priming pulse is carried out, for example, once for eachsubfield in order to enhance the discharge stability of the PDP.However, the priming discharge involves applying discharges to alldischarge cells on the full screen at once to cause luminescencecorresponding to a certain gradation level, resulting in low contrast.On the other hand, the decrease in the frequency of generation of thepriming pulse leads to low discharge stability.

On the other hand, the decrease in the frequency of generation of thepriming pulse leads to low discharge stability.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, a plasma displaydevice comprises: control signal output means for outputting a controlsignal responsive to the signal format of an input video signal; anddriving means for driving a plasma display panel based on the controlsignal outputted from the control signal output means.

Preferably, according to a second aspect of the present invention, theplasma display device of the first aspect further comprises: signalformat identifying means for identifying the signal format of the inputvideo signal, the signal format identifying means applying to thecontrol signal output means an identification output responsive to thesignal format of the input video signal.

Preferably, according to a third aspect of the present invention, in theplasma display device of the second aspect, the control signal outputmeans includes selecting means for selecting one of a plurality ofpreviously determined pieces of control information based on theidentification output; and the control signal is provided based on theselected piece of control information.

Preferably, according to a fourth aspect of the present invention, inthe plasma display device of the third aspect, the pieces of controlinformation include the number of subfields which is previouslydetermined in response to the signal format of the input video signal;and one field time period is divided into subfield time periods thenumber of which equals the number of subfields for representation ofgradation.

Preferably, according to a fifth aspect of the present invention, in theplasma display device of the third aspect, the pieces of controlinformation include frequency with which a priming pulse is generatedper field, the frequency being previously determined in response to thesignal format of the input video signal.

Preferably, according to a sixth aspect of the present invention, in theplasma display device of the fourth aspect, whether or not to divide theone field time period into the subfield time periods the number of whichis greater than the minimum number of subfields required to representthe gradation in order to prevent a pseudo contour of a moving pictureis controlled in response to the signal format of the input videosignal.

Preferably, according to a seventh aspect of the present invention, inthe plasma display device of the third aspect, the pieces of controlinformation include a set value for write time per cell, the set valuefor write time being previously determined in response to the signalformat of the input video signal; and a write operation of data into theplasma display panel is controlled based on the set value for writetime.

Preferably, according to an eighth aspect of the present invention, inthe plasma display device of the third aspect, the pieces of controlinformation include the number of sustain pulses per field for an APL,the number of sustain pulses being previously determined in response tothe signal format of the input video signal; and APC characteristics arechanged based on the number of sustain pulses.

Preferably, according to a ninth aspect of the present invention, in theplasma display device of the third aspect, the pieces of controlinformation include the number of sustain pulses per field, the numberof sustain pulses being previously determined in response to the signalformat of the input video signal.

Preferably, according to a tenth aspect of the present invention, in theplasma display device of the third aspect, the pieces of controlinformation include color temperature conversion characteristics ofimage data, the color temperature conversion characteristics beingpreviously determined in response to the signal format of the inputvideo signal.

According to an eleventh aspect of the present invention, a method ofdriving a plasma display comprises the steps of: outputting a controlsignal in response to the signal format of an input video signal; anddriving a plasma display panel based on the control signal.

Preferably, according to a twelfth aspect of the present invention, inthe method of the eleventh aspect, the control signal is generated basedon an identification output responsive to the signal format of the inputvideo signal.

Preferably, according to a thirteenth aspect of the present invention,in the method of the twelfth aspect, the control signal is providedbased on one piece of control information selected in response to theidentification output among a plurality of previously prepared pieces ofcontrol information.

Preferably, according to a fourteenth aspect of the present invention,in the method of the thirteenth aspect, the pieces of controlinformation include the number of subfields which is previouslydetermined in response to the signal format of the input video signal;and one field time period is divided into subfield time periods thenumber of which equals the number of subfields for representation ofgradation.

Preferably, according to a fifteenth aspect of the present invention, inthe method of the thirteenth aspect, the pieces of control informationinclude frequency with which a priming pulse is generated per field, thefrequency being previously determined in response to the signal formatof the input video signal.

Preferably, according to a sixteenth aspect of the present invention, inthe method of the fourteenth aspect, whether or not to divide the onefield time period into the subfield time periods the number of which isgreater than the minimum number of subfields required to represent thegradation in order to prevent a pseudo contour of a moving picture iscontrolled in response to the signal format of the input video signal.

Preferably, according to a seventeenth aspect of the present invention,in the method of the thirteenth aspect, the pieces of controlinformation include a set value for write time per cell, the set valuefor write time being previously determined in response to the signalformat of the input video signal; and a write operation of data into theplasma display panel is controlled based on the set value for writetime.

Preferably, according to an eighteenth aspect of the present invention,in the method of the thirteenth aspect, the pieces of controlinformation include the number of sustain pulses per field for an APL,the number of sustain pulses being previously determined in response tothe signal format of the input video signal; and APC characteristics arechanged based on the number of sustain pulses.

Preferably, according to a nineteenth aspect of the present invention,in the method of the thirteenth aspect, the number of sustain pulses isin inverse proportion to the frequency of a vertical synchronizationsignal in the input video signal.

Preferably, according to a twentieth aspect of the present invention, inthe method of the thirteenth aspect, the pieces of control informationinclude color temperature conversion characteristics of image data, thecolor temperature conversion characteristics being previously determinedin response to the signal format of the input video signal.

In accordance with the first aspect of the present invention, thecontrol signal responsive to the signal format of the input video signalis outputted, and the PDP is driven based on the control signal. Thus,the PDP may be driven under different driving conditions for each signalformat of the input video signal. The PDP may be optimally driven inresponse to individual video signals while taking full advantage ofhigher-priority characteristics determined by the input video signalunder various restrictive conditions presented when the input videosignal is displayed on the PDP (e.g., the sequence time which isoriginally required for optimum display on the PDP is limited by thevideo signal; a luminance and the suppression of the degree of stickingconflict with each other; and display contrast and display stabilityconflict with each other).

In accordance with the second aspect of the present invention, thecontrol signal output means outputs the control signal in response toand based on the signal format of the input video signal identified bythe signal format identification means. This allows the plasma displayto be automatically driven in response to the signal format of the inputvideo signal.

In accordance with the third aspect of the present invention, thecontrol signal is provided based on the selected one of the plurality ofpieces of control information possessed by the control signal outputmeans. The preparation of optimum driving conditions responsive to thesignal format of the input video signal as the control informationensures the setting of the optimum driving conditions.

In accordance with the fourth aspect of the present invention, thegradation is represented by dividing the one field time period into theplurality of subfield time periods, and the number of subfields isdetermined according to the respective signal formats of the input videosignal. Depending upon the signal format of the input video signal, thenumber of gradation levels is preferably greater in some cases, and neednot be so great in other cases. The optimum number of gradation levelsmay be set in accordance with such requirements. In particular, thesetting of a greater number of gradation levels allows smooth display,and the setting of a smaller number of gradation levels provides aresultant time margin to be used to enhance other characteristics.

In accordance with the fifth aspect of the present invention, thefrequency with which the priming pulse is generated per field is set inresponse to the signal format of the input video signal. Depending onthe signal format of the input video signal, the contrast is preferablyhigh in some cases and need not be so high in other cases. Further,flicker is conspicuous in some cases and is not so conspicuous in othercases. The fifth aspect of the present invention provides an optimumdisplay image (e.g., an image having not so high contrast but highdisplay stability with less flicker, or an image having not so highdisplay stability but high contrast) for each signal format of the inputvideo signal as the case may be.

In accordance with the sixth aspect of the present invention, whether ornot to divide the one field time period into the subfield time periodsthe number of which is greater than the minimum number of subfieldsrequired to represent the gradation in order to prevent the pseudocontour of the moving picture is controlled in response to the signalformat of the input video signal. Depending on the signal format of theinput video signal, the moving picture pseudo contour is a significantproblem in some cases and is not so significant in other cases. As thecase may be, the moving picture pseudo contour is suppressed in responseto the input video signal for which the pseudo contour is the problem,and measures against the moving picture pseudo contour need not be takenin response to the input video signal for which the pseudo contour isnot so significant. The time margin provided by the non-execution of themeasures against the moving picture pseudo contour may be used toenhance other characteristics.

In accordance with the seventh aspect of the present invention, thewrite time per cell during the write operation of data into the PDP ispreviously determined in response to the signal format of the inputvideo signal. Depending on the signal format of the input video signal,flicker is a significant problem in some cases and is not so significantin other cases. For the input video signal for which flicker is thesignificant problem, the write time is elongated to increase the displaystability, providing the image with less flicker. For the input videosignal for which flicker is not so significant, the write time may beshortened, and the resultant time margin may be used to enhance othercharacteristics.

In accordance with the eighth aspect of the present invention, thenumber of sustain pulses per field for the APL is previously determinedin response to the signal format of the input video signal. For theinput video signal for which burning is a significant problem, the APCcharacteristics are changed so that the peak luminance is suppressed toprevent the sticking. For the input video signal for which the burningis not so significant, the APC characteristics are changed so that thepeak luminance is increased to provide a well-contrasted image.

In accordance with the ninth aspect of the present invention, the numberof sustain pulses per field is changed in response to the signal formatof the input video signal. Thus, the screen is displayed with aluminance suitable for the input video signal.

In accordance with the tenth aspect of the present invention, thecharacteristics of color temperature conversion processing performed onimage data are changed in response to the signal format of the inputvideo signal. This provides an image having the optimum relationshipbetween the color temperature and the luminance in response to thesignal format of the input video signal under such PDP displayrestrictive conditions that the increase in color temperature requiresthe decrease in luminance.

In accordance with the eleventh aspect of the present invention, thecontrol signal responsive to the signal format of the input video signalis outputted, and the PDP is driven based on the control signal. Thus,the PDP may be driven under different driving conditions for each signalformat of the input video signal. The PDP may be optimally driven inresponse to individual video signals while taking full advantage ofhigher-priority characteristics determined by the input video signalunder various restrictive conditions presented when the input videosignal is displayed on the PDP (e.g., the sequence time which isoriginally required for optimum display on the PDP is limited by thevideo signal; the luminance and the suppression of the degree ofsticking conflict with each other; and the display contrast and thedisplay stability conflict with each other).

In accordance with the twelfth aspect of the present invention, thecontrol signal is generated based on the identification outputresponsive to the signal format of the input video signal. This allowsthe plasma display to be automatically driven in response to the signalformat of the input video signal.

In accordance with the thirteenth aspect of the present invention, thecontrol signal is provided based on the selected one of the plurality ofpieces of control information. The preparation of optimum drivingconditions responsive to the signal format of the input video signal asthe control information ensures the setting of the optimum drivingconditions.

In accordance with the fourteenth aspect of the present invention, thegradation is represented by dividing the one field time period into theplurality of subfield time periods, and the number of subfields isdetermined according to the respective signal formats of the input videosignal. Depending upon the signal format of the input video signal, thenumber of gradation levels is preferably greater in some cases, and neednot be so great in other cases. The optimum number of gradation levelsmay be set in accordance with such requirements. In particular, thesetting of a greater number of gradation levels allows smooth display,and the setting of a smaller number of gradation levels provides aresultant time margin to be used to enhance other characteristics.

In accordance with the fifteenth aspect of the present invention, thefrequency with which the priming pulse is generated per field is set inresponse to the signal format of the input video signal. Depending onthe signal format of the input video signal, the contrast is preferablyhigh in some cases and need not be so high in other cases. Further,flicker is conspicuous in some cases and is not so conspicuous in othercases. The seventeenth aspect of the present invention provides anoptimum display image (e.g., an image having not so high contrast buthigh display stability with less flicker, or an image having not so highdisplay stability but high contrast) for each signal format of the inputvideo signal as the case may be.

In accordance with the sixteenth aspect of the present invention,whether or not to divide the one field time period into the subfieldtime periods the number of which is greater than the minimum number ofsubfields required to represent the gradation in order to prevent thepseudo contour of the moving picture is controlled in response to thesignal format of the input video signal. Depending on the signal formatof the input video signal, the moving picture pseudo contour is asignificant problem in some cases and is not so significant in othercases. As the case may be, the moving picture pseudo contour issuppressed in response to the input video signal for which the pseudocontour is the problem, and measures against the moving picture pseudocontour need not be taken in response to the input video signal forwhich the pseudo contour is not so significant. The time margin providedby the non-execution of the measures against the moving picture pseudocontour may be used to enhance other characteristics.

In accordance with the seventeenth aspect of the present invention, thewrite time per cell during the write operation of data into the PDP ispreviously determined in response to the signal format of the inputvideo signal. Depending on the signal format of the input video signal,flicker is a significant problem in some cases and is not so significantin other cases. For the input video signal for which flicker is thesignificant problem, the write time is elongated to increase the displaystability, providing the image with less flicker. For the input videosignal for which flicker is not so significant, the write time may beshortened, and the resultant time margin may be used to enhance othercharacteristics.

In accordance with the eighteenth aspect of the present invention, thenumber of sustain pulses per field for the APL is previously determinedin response to the signal format of the input video signal. For theinput video signal for which burning is a significant problem, the APCcharacteristics are changed so that the peak luminance is suppressed toprevent the sticking. For the input video signal for which burning isnot so significant, the APC characteristics are changed so that the peakluminance is increased to provide a well-contrasted image.

In accordance with the nineteenth aspect of the present invention, thenumber of sustain pulses per field is changed in response to the signalformat of the input video signal. Thus, the screen is displayed with aluminance suitable for the input video signal.

In accordance with the twentieth aspect of the present invention, thecharacteristics of color temperature conversion processing performed onimage data are changed in response to the signal format of the inputvideo signal. This provides an image having the optimum relationshipbetween the color temperature and the luminance in response to thesignal format of the input video signal under such PDP displayrestrictive conditions that the increase in color temperature requiresthe decrease in luminance.

It is therefore an object of the present invention to provide a plasmadisplay device and a method of driving a plasma display which providebetter display control in response to the signal format of an inputsignal.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram showing the general construction of a plasmadisplay device according to a preferred embodiment of the presentinvention;

FIG. 1B is a block diagram showing the general construction of aconventional plasma display device for comparison with that of FIG. 1A;

FIG. 2 is a block diagram showing the general construction of the plasmadisplay device according to the preferred embodiment of the presentinvention;

FIGS. 3A and 3B illustrate the control of the number of gradation levelsin the plasma display device according to the preferred embodiment ofthe present invention;

FIG. 4 illustrates measures against a moving picture pseudo contour inthe plasma display device according to the preferred embodiment of thepresent invention;

FIG. 5 is a sectional view of a discharge cell in the plasma displaydevice according to the preferred embodiment of the present invention;

FIGS. 6A and 6B are timing charts illustrating simultaneous two-linewriting in the plasma display device according to the preferredembodiment of the present invention;

FIG. 7 illustrates APC characteristic control in the plasma displaydevice according to the preferred embodiment of the present invention;

FIG. 8 is a timing chart illustrating the timing of generation of apriming pulse P in the plasma display device according to the preferredembodiment of the present invention; and

FIGS. 9A and 9B illustrate the timing of generation of the priming pulseP and the elongation of a write time in the plasma display deviceaccording to the preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will now be describedwith reference to the drawings.

FIG. 1A is a block diagram showing the general construction of a plasmadisplay device according to a preferred embodiment of the presentinvention. FIG. 1B is a block diagram showing the construction of aconventional plasma display device for comparison with that of FIG. 1A.

A plurality of video inputs (video inputs A and B in FIGS. 1A and 1B)are applied to an input-by-input signal processing portion 11. Theinput-by-input signal processing portion 11 comprises signal processingportions 12 and 13 corresponding to the video inputs A and B,respectively. Video signals processed in the input-by-input signalprocessing portion 11 are applied to a PDP module portion 14. The PDPmodule portion 14 comprises a video signal processing portion 15, acontrol signal generating portion 16, a driving portion 17, and adisplay panel 18.

The PDP module portion 14 receives a digital image signal comprising,for example, 8 bits for each of RBG, vertical and horizontalsynchronization signals, and a dot clock. The video signal processingportion 15 mainly performs signal processing inherent in the PDP, suchas sorting of image data. For instance, upon receipt of respective 8-bitsignals for RGB in parallel, the video signal processing portion 15performs processing such as sorting of the signals in the order ofgradation bits so as to conform to the subfield gradation technique, andthen transmits processed data to the driving portion 17.

The control signal generating portion 16 includes a storage element suchas a ROM for storing information about a PDP driving sequence, andoutputs a sequence control signal based on the information. The sequencecontrol signal is applied to the driving portion 17 and the video signalprocessing portion 15.

The driving portion 17 applies drive pulses such as a priming pulse, anaddress pulse, and a sustain pulse to the display panel 18 based on thesequence control signal from the control signal generating portion 16and the video signal from the video signal processing portion 15.

The video inputs A and B to the plasma display device include atelevision signal such as NTSC and a graphic signal such as VGA. Theformats of these signals must be made compatible with the input formatof the PDP module portion 14. In the conventional plasma display device,the input-by-input signal processing portion 11 comprising the signalprocessing portions 12 and 13 corresponding respectively to the videoinputs A and B is provided ahead of the PDP module portion 14 so thatthe signal processing portions 12 and 13 perform sync separation, videodemodulation, A/D conversion and scanning line interpolation on the NTSCsignal and perform only A/D conversion on the VGA signal to convert thevideo input signals into signals independent of signal formats to outputthe resultant signals to the PDP module portion 14.

The plasma display device according to the preferred embodiment of thepresent invention comprises a signal format identification portion 19 inaddition to the conventional construction so that the result ofidentification in the signal format identification portion 19 is appliedto the control signal generating portion 16. Further, the control signalgenerating portion 16 is variable for changing the PDP driving sequenceand an image signal processing scheme based on the identification resultfrom the signal format identification portion 19.

Such an arrangement allows the PDP to be driven under differentconditions depending on the input video signals. Thus, under variousrestrictive conditions for displaying the input video signals on thePDP, the PDP is optimally driven in response to the video signal formatwhile taking full advantage of higher-priority characteristicsdetermined by the input video signals. Additionally, since the operationof the PDP module portion 14 is variable in response to the input videosignals, the conventional conversion of the input video signals into thesame signal format in the input-by-input signal processing portion 11may be replaced with equivalent processing using the driving sequence.In this manner, some of the operations of the input-by-input signalprocessing portion 11 are simplified. Furthermore, the procedure of aseries of processes from the signal processing to the driving sequencemay be optimized in accordance with the signal format of the input videosignals.

FIG. 2 is a block diagram of an arrangement of the plasma display deviceof FIG. 1A for practical application.

The plasma display device shown in FIG. 2 may receive as input signals atelevision signal (NTSC, PAL and the like) and a graphic signal (VGA,XGA) from a personal computer. One of the television signal and thegraphic signal is selectively applied to the plasma display device,subjected to predetermined processing, and displayed on a display panel8. The television signal is applied to a sync separation circuit 1whereas the graphic signal is applied to a sync separation circuit 2.The sync separation circuits 1 and 2 extract vertical and horizontalsynchronization signals from the input signal. Some of the graphicsignals contain synchronization signals which are inputted after beingseparated, and in this case the sync separation circuit 2 is notrequired.

The video signals obtained by extracting the synchronization signals areapplied to a video signal processing circuit 3 and converted to digitalimage data for display. Specifically, the video signal processingcircuit 3 performs video demodulation, inverted gamma correction, colortemperature conversion, sorting of image data, and the like. Thesynchronization signals extracted in the sync separation circuits 1 and2 are applied to a signal format identification circuit 4. The signalformat identification circuit 4 identifies (i) whether the input signalis the television signal or the graphic signal; (ii) whether the inputsignal is an NTSC signal, a PAL signal, or an SECAM signal if it is thetelevision signal; and (iii) whether the input signal is a VGA signal oran XGA signal if it is the graphic signal.

The identification of the signal format in the signal formatidentification circuit 4 is accomplished using techniques to bedescribed below. The techniques which may be suitably adopted include(i) identifying whether the input signal is the television signal or thegraphic signal depending on whether the synchronization signal isinputted from the sync separation circuit 1 for the television signal orthe synchronization signal is inputted from the sync separation circuit2 for the graphic signal; (ii) discriminating between the televisionsignal and the graphic signal and identifying signal formats of thetelevision signal and the graphic signal based on periods of thesynchronization signal which are counted using a fixed clock; (iii)discriminating between the television signal and the graphic signal andidentifying signal formats of the television signal and the graphicsignal based on the counted number of horizontal synchronization signalsamong vertical synchronization signals, and (iv) discriminating betweenthe television signal and the graphic signal and identifying signalformats of the television signal and the graphic signal based on thepolarities of the vertical and horizontal synchronization signals. Thesignal format is sometimes identified based on the character of an imagediscriminating between a moving picture and a still picture and also maybe identified in consideration for both the synchronization signal andthe character of an image discriminating between a moving picture and astill picture. A signal type input entered via a manual switch may beused as the signal format identification signal without employing theabove discussed automatic identification.

The signal format identification circuit 4 produces the signal formatidentification signal in response to the detected signal format toapplies the signal format identification signal to a mode-by-modecontrol signal generating circuit 5. The mode-by-mode control signalgenerating circuit 5 contains a plurality of pieces of control signalinformation 6(1) to 6(n) corresponding to respective modes. The signalformat identification signal outputted from the signal formatidentification circuit 4 is applied to a selector 9 provided in themode-by-mode control signal generating circuit 5. The selector 9 selectsone of the pieces of control signal information 6(1) to 6(n) based onthe signal format identification signal to apply the selected piece ofcontrol signal information to a control signal generating circuit 10.Based on the applied piece of control signal information, the controlsignal generating circuit 10 generates various sequence control signalscorresponding to respective signal formats. The sequence control signalsare applied to the video signal processing circuit 3 and a drivingcircuit 7.

The video signal processing circuit 3 performs predetermined processingon the video signals given from the sync separation circuits 1 and 2.The predetermined processing includes, for example, video demodulation,gamma correction, and color temperature correction, but differentprocesses are performed on the video signals depending on the differentsequence control signals given from the mode-by-mode control signalgenerating circuit 5. The driving circuit 7 generates a predetermineddrive pulse in response to the image data from the video signalprocessing circuit 3 and the sequence control signals from themode-by-mode control signal generating circuit 5 to drive the displaypanel 8 using the predetermined drive pulse. This causes luminescenceresponsive to the image data on the display panel 8.

In the plasma display device of the preferred embodiment, the PDPdriving scheme is controlled in response to the sequence control signalsfrom the mode-by-mode control signal generating circuit 5 which in turncontains the plurality of pieces of control signal information 6(1) to6(n) corresponding to the respective signal formats of the video input.If the signal format identification circuit 4 identifies that the videoinput is, for example, an NTSC television signal, the selector 9 selectsand outputs a piece of control signal information corresponding to theNTSC signal among the pieces of control signal information 6(1) to 6(n),and the control signal generating circuit 10 generates the correspondingdriving sequence based on the piece of control signal informationoutputted from the selector 9. The PDP is thus driven in response to thesignal format of the input video signal to achieve optimum display.

Items changeable depending on the signal format of the input signal inthe driving method are described below. Suitably changing the controlcontents of these items in accordance with the signal format of theinput signal achieves optimum display.

The items are as follows:

(A) The number of gradation levels

(B) The adoption/non-adoption of measures against a moving picturepseudo contour (subdivision of subfields and the like)

(C) Writing Sequence (whether the interlace/non-interlace conversion isperformed by signal processing or the interlace signal is written as itis into two lines so that the driving sequence conforms to the interlacesignal)

(D) APC characteristics

(E) The number of times of a priming discharge per field

(F) Write time per cell

(G) The number of sustain pulses per field

(H) Color temperature conversion

These items are specifically described hereinafter.

(A) The Number of Gradation Levels

The plasma display device according to the preferred embodiment of thepresent invention controls the driving circuit 7 in response to thesignal format of the input signal to control the number of gradationlevels for display on the display panel 8. Specifically, whether theinput signal is the graphic signal or the television signal isrecognized based on the signal format identification signal from thesignal format identification circuit 4. Then, the mode-by-mode controlsignal generating circuit 5 selects and outputs one of the pieces ofcontrol signal information 6(1) to 6(n) in response to the recognizedsignal format. Accordingly, the sequence control signal to be applied tothe driving circuit 7 is changed in response to the signal format of theinput signal, and the number of gradation levels in the display panel 8is also changed. For example, 64-level gradation with 6 subfields isemployed if the input signal is the graphic signal, and 256-levelgradation with 8 subfields is employed if the input signal is thetelevision signal.

In the case of the graphic signal, as shown in FIG. 3A, the displaypanel is driven using six subfields SF1 (corresponding to the MSB ofimage data) to SF6 (corresponding to the LSB of the image data). In thecase of the television signal, as shown in FIG. 3B, the display panel isdriven using eight subfields SF1 (corresponding to the MSB of imagedata) to SF8 (corresponding to the LSB of the image data). Then,luminance control with 64-level gradation is performed on the graphicsignal whereas luminance control with 256-level gradation is performedon the television signal.

The drive operation in one subfield is performed in the following order:(i) a priming discharge by means of one priming pulse, (ii) writing inresponse to data of a given bit for each horizontal line by means of awrite pulse, and (iii) luminescence by means of a sustain pulse. InFIGS. 3A and 3B, the time periods for the operations (i) to (iii) areindicated respectively by the blank and “P”, the line slanted downwardto the right, and the horizontal parallel lines.

The drive operation in the subfield SF1 corresponding to the MSB of theimage data, for example, is contemplated. The driving circuit 7initially applies a high voltage to all discharge cells using Xelectrodes extending in the vertical direction in response to a primingpulse to cause luminescence on the full screen. Next, the drivingcircuit 7 is supplied with the MSBs of the image data of all pixels (ndischarge cells arranged in the horizontal direction by m dischargecells arranged in the vertical direction) from the video signalprocessing circuit 3, and the driving circuit 7 controls whether toapply voltage or not to each discharge cell in each horizontal line inresponse to the data “1” and “0” for each pixel to provide a wall chargeto each discharge cell (write data in each discharge cell). The drivingcircuit 7 then applies a sustain pulse to all discharge cells to causeonly the discharge cells to which the wall charge has been provided toproduce a discharge. Upon completion of the drive operation in thesubfield corresponding to the MSB, the drive operation using the data ofthe subsequent bits is performed in sequential order. The sequentialreduction in the time period for which the sustain pulse is appliedduring the drive operation by half allows the discharge in one field toconform to the image data.

The increase in the number of gradation levels permits accordinglyminute control of the gradation levels and smooth display, but alsoaccordingly increases the number of subfields, making difficult theprocessing within a predetermined one-field time period. Morespecifically, display with 256-level gradation requires eight subfields,resulting in lack of processing time in some cases even by the full useof one-field time as shown in FIG. 3B. On the other hand, display with64-level gradation requires only six subfields to provide a time marginas shown in FIG. 3A.

A television image is generally a natural image which often shows smoothchange in gradation. Thus, it is desired to display the television imagewith more levels of gradation. The 256-level gradation allows suitabledisplay to human eyes.

On the other hand, a graphic image produced using a computer has aclearly distinct contour. Thus, the graphic image does not require somany gradation levels, and the 64-level gradation allows display whichpresents no visual problem. As described above, display with 64-levelgradation produces the time margin which in turn may be utilized toperform other processes including, for example, the process ofprolonging the write time for providing a wall charge to render thesubsequent discharge more stable. In contrast with this, if time isinsufficient to display the television signal with 256-level gradation,one-line data may be simultaneously written into two lines by utilizingthe fact that the television signal is generally an interlace signal,thereby reducing time. These processes will be described later.

(B) Adoption/Non-adoption of Measures Against Moving Picture PseudoContour

In accordance with the preferred embodiment of the present invention,whether to take measures against the moving picture pseudo contour ornot is controlled depending on whether the input signal is thetelevision signal or the graphic signal.

The measures against the moving picture pseudo contour include theprocess of subdividing the subfield corresponding to the MSB asdisclosed in, for example, U.S. Pat. No. 5,187,578. More specifically,the subfield SF1 is divided into two subfields SF1A and SF1B and thesubfield SF1B is positioned to follow the subfield SF8 corresponding tothe LSB, as shown in FIG. 4. In this manner, dividing the subfieldhaving a long luminescence time period into the two subfields andplacing the two subfields respectively at the first and last locationsof one field may provide uniform time for luminescence and suppress theoccurrence of the moving picture pseudo contour. This technique,however, increases the number of subfields to require longer time forone-field display.

The measures against the moving picture pseudo contour may includedividing not only the subfield corresponding to the MSB but also thesubfield corresponding to the second most significant bit. Further, atechnique as disclosed in Japanese Patent Application No.P08-147198(1996) may be used which produces two luminance ratio patternsto switch therebetween for each discharge cell, rather than setting theluminance ratio (luminescence time by means of the sustain pulse) of thesubfields to 2^(n). In either method, however, the number of subfieldsis similarly increased and it takes longer time for one-field display.

The preferred embodiment of the present invention takes the measuresagainst the moving picture pseudo contour if the input signal is thetelevision signal and does not take the measures if the input signal isthe graphic signal. An image on the television screen is a natural imagecontaining a moving picture with smoothly changing gradation, and henceis prone to produce a moving picture pseudo contour. For this reason,the above described measures against the moving picture pseudo contourare taken if the input signal is the television signal. On the otherhand, a graphic image often contains no high-quality moving pictures,and in few cases presents the problem of the moving picture pseudocontour. For this reason, the measures against the moving picture pseudocontour are not taken if the input signal is the graphic signal. Thisprovides a time margin to be used for other processes.

(C) Writing Sequence

In the preferred embodiment of the present invention, the writingsequence for displaying the input video signal inputted in the form ofan interlace signal or a non-interlace signal on the PDP is changed inresponse to the input signal. To display the interlace signal on thePDP, it is a common practice to produce new line data interpolatedbetween upper and lower scanning lines to convert the interlace signalinto a non-interlace signal. As disclosed in Japanese Patent ApplicationLaid-Open No. P05-216433A (1993), the process of writing one-line datainto two lines may be performed. This process eliminates the need toconvert the interlace signal into the non-interlace signal and reducethe write time.

The operation of the above described process is discussed with referenceto FIGS. 5, 6A and 6B. FIG. 5 is a sectional view of a cell of the PDP.In FIG. 5, the reference character X designates a sustain electrode, andYi designates a scan electrode. The sustain electrode X and the scanelectrode Yi are both formed on a glass substrate 21. The referencenumeral 22 designates a dielectric layer formed on the sustain electrodeX and the scan electrode Yi; 23 designates a protective layer formed onthe dielectric layer 22; the reference character Aj designates anaddress electrode formed on a glass substrate 24 opposed to the glasssubstrate 21; 25 designates a dielectric layer formed on the addresselectrode; 26 designates a barrier rib formed on the boundary betweenadjacent cells; 27 designates a phosphor; and 28 designates a dischargespace filled with, for example, a gas mixture of neon and xenon.

FIG. 6A is a timing chart showing a one-subfield operation when anodd-numbered field data is inputted. Initially, a priming pulse P isapplied to the sustain electrode X. Then, a wall charge is provided to(data is written to) an object discharge cell in response to data D1 inthe first line of the address electrode Aj. At this time, the wallcharge is provided using the same data in the first line to the secondline as well as to the first line. Specifically, data is written intodischarge cells in the first and second horizontal lines having data “1”by applying the scan pulse to scan electrodes Y1 and Y2 and applyingvoltage based on the data D1 to the address electrode Aj. Similar writeoperation is performed on the discharge cells in the third andsubsequent lines so that data in (2k−1)th line is written into (2k−1)thand (2k)th lines until all discharge cells are written in response todata. The sustain pulse is applied alternately to the scan electrode Yiand the sustain electrode X to cause some of all discharge cells whichreceive the wall charge to produce a discharge to illuminate. Theabove-described processing is performed repeatedly on all subfieldsuntil one-field display is completed.

FIG. 6B is a timing chart showing a one-subfield operation when aneven-numbered field data is inputted. In an even-numbered field, data iswritten into two lines, for example, in such a manner that theeven-numbered line data D2 and D4 are written into the second and thirdlines and the fourth and fifth lines, respectively.

The simultaneous two-line writing eliminates the need for aninterpolation operation of data and accordingly a logic circuit forexecuting the interpolation operation. Additionally, two-line writingcan be performed by writing data once. This reduces the time requiredfor writing to half the time required for writing in the case of thetypical non-interlace signal, thereby providing a time margin. Then,time for the above described increase in the number of gradation levelsand measures against the moving picture pseudo contour is obtained.However, the use of such a driving method results in the same display intwo lines, which decreases the resolution of the image and causes someflicker.

Examples of the television signal include a PAL signal and a SECAMsignal as well as the NTSC signal. These signals differ from each otherin the number of fields per second and the number of scanning lines. Forexample, the PAL signal generally provides 50-field display per second,that is, provides more time margin per field than the NTSC signal. Aninterpolation operation is required to display the PAL signal on the PDPwhich has the resolution tailored to the NTSC signal since the PALsignal differs in the number of scanning lines from the NTSC signal.Therefore, in the preferred embodiment of the present invention, the PDPresolution is tailored to the NTSC signal, and the above statedsimultaneous two-line writing technique is used to display the NTSCsignal whereas the interpolation operation based on the upper and lowerscanning lines and the conversion into the non-interlace signal areperformed to display the PAL signal.

Changing the driving method in this manner in response to the signalformat of the input signal offers following advantages:

In displaying the NTSC signal,

(1) Although there has been no time margin because of the 60-fielddisplay per second, the simultaneous two-line writing provides a timemargin.

(2) The need for a circuit for executing the interpolation operation iseliminated.

In displaying the PAL signal,

(1) The conversion into the non-interlace signal by interpolationprovides a high-resolution image with a small amount of flicker.

(2) The 50-field display per second provides a relatively sufficienttime margin without the execution of the simultaneous two-line writing.

(3) The interpolation operation may be shared with a processing circuitfor converting the resolution of the PAL signal to that of the NTSCsignal.

As above described, the preferred embodiment may suitably drive the PDPin response to the respective signal formats.

If the input signal has other signal formats, for example, a VGA signalbut is originally the non-interlace signal, the signal is displayed asthe non-interlace signal. The time margin which may be produced byreducing the number of gradation levels or taking no measures againstthe moving picture pseudo contour such as subfield division presents noproblem.

(D) APC Characteristics

In this preferred embodiment, the APC (automatic power control)characteristics are changed depending on whether the input signal is thetelevision signal or the graphic signal as shown in FIG. 7. The APC ofthe plasma display is carried out by increasing/decreasing the number ofsustain pulses per field according to the APL so that a constant maximumluminance (peak luminance) is reached for a low APL and the luminancedecreases as the APL increases, as indicated by the APL versus luminancecharacteristic of FIG. 7. This suppresses power consumption at a fixedlevel when the APL is high as indicated by the APL versus powerconsumption characteristic of FIG. 7.

If the input signal is the graphic signal, the peak luminance is set toa low level when the APL is low as indicated by the broken line of FIG.7. For the graphic signal often representing an unmoving image, theluminance which is set too high might cause sticking at the associateddischarge cell. Thus, the peak luminance for the graphic signal may besuppressed to prevent the occurrence of the sticking. On the other handsif the input signal is the television signal, a well-contrasted image isachieved by setting the peak luminance to a high level when the APL islow. As indicated by the APL versus power consumption characteristic ofFIG. 7, the luminance of the television signal for a high APL is set toa level similar to that provided when the input signal is the graphicsignal. This reduces the maximum power consumption of the televisionsignal to a level similar to that of the graphic signal.

(E) The Number of Times of Priming Discharge per Field

In this preferred embodiment, the frequency with which the priming pulseP causes the write discharge at all cells is changed in response to theinput signal. Referring to FIG. 8, if the input signal is the televisionsignal, the priming pulses P are not generated in all subfields, butsome of the priming pulses P are replaced with erase pulses E of anarrow width.

More specifically, the priming pulse P is generated in the firstsubfield. All discharge cells are discharged at the rising edge of thepriming pulse, and the wall charge is erased in all discharge cells atthe falling edge of the priming pulse. In the next subfield, thenarrow-width erase pulse E is inserted in place of the priming pulse P.Such a narrow-width erase pulse E allows an erase discharge to beproduced only at the cells in which a sustain operation has beenperformed in the previous subfield, but does not cause all dischargecells to be discharged unlike the priming pulse.

The use of the narrow-width erase pulse E in place of the priming pulseP may increase an image contrast to aid in enhancing the contrast of thetelevision image.

The priming pulse is to provide the full write discharge at alldischarge cells. Thus, the discharge caused by the priming pulse Prather than the narrow-width erase pulse maintains more positivelyuniform wall charges at the discharge cells to enhance the dischargestability and to reduce discharge failures at the discharge cells. Forthe television image which contains a large number of moving picturesconstantly changing throughout the image, some discharge failures oftendo not constitute a matter of concern, but a high contrast is ratherpreferable. On the other hand, for the graphic signal often representinga still picture, the image to be displayed has a clear contour andexhibits a relatively even luminance change. Thus, in the case of stillimage display which shows conspicuous flicker due to the dischargefailures, it is preferable to generate priming pulses P with increasedfrequency in each subfield, such as the production of the full writedischarge by the priming pulses P, in order to ensure wall chargeerasing.

As stated above, the number of priming pulses per field is decreased ifthe input signal is the television signal, and is increased if the inputsignal is the graphic signal. This provides a high-contrast televisionimage and a flicker-reduced graphic image.

(F) Write Time Per Cell

In this preferred embodiment, the time required to write data is changedin response to the signal format of the input signal as shown in FIGS.9A and 9B. The set value for write time is included in the pieces ofcontrol signal information 6(1) to 6(n), whereby the write time for thegraphic signal shown in FIG. 9B is made longer than the write time forthe television signal shown in FIG. 9A, for example. That is, the writetime is made longer when the input signal is the graphic signal. Thisensures the supply of the wall charge by writing data at each dischargecell to ameliorate the flicker resulting from the discharge failures onthe screen of the graphic image. When the input signal is the televisionsignal, the write time is shortened to provide a time margin which maybe used to increase the number of gradation levels and to divide thesubfield as measures against the pseudo contour. For instance, for thetelevision signal, eight subfields constitute one field and the primingpulses P are generated in the first and fourth subfields as shown inFIG. 9A. This achieves multi-level gradation and the prevention of themoving picture pseudo contour as well as providing a well-contrastedimage. For the graphic signal, six subfields constitute one field toelongate the data write time as shown in FIG. 9B, and the priming pulsesP are generated in the first, third and fifth subfields. This ensuresthe write discharge to suppress the flicker resulting from the dischargefailures on the screen.

(G) The Number of Sustain Pulses Per Field

In this preferred embodiment, the number of sustain pulses per field ischanged in response to the input signal when a one-field period indriving the PDP is synchronized with the vertical synchronization signalin the input signal. This change is made to solve such a problem that ascreen brightness changes depending on the signal format if the numberof sustain pulses per field is fixed since the number of fields persecond (vertical synchronization frequency) differs depending on thesignal format. For example, if consideration is given on the basis ofthe NTSC signal, the number of sustain pulses per unit timesubstantially decreases to lower the luminance when the verticalsynchronization frequency of the input signal is lower than that of theNTSC signal.

To solve the above described problem, the number of sustain pulses isincreased/decreased or in inverse proportion to the verticalsynchronization frequency. For instance, the number of sustain pulsesfor the PAL signal (50 Hz) may be made 1.2 times greater than that forthe NTSC signal (60 Hz) to achieve the same level of luminance for theNTSC signal and the PAL signal.

More specifically, the driving sequence of the display panel 8 ischanged in response to the signal format of the input signal to drivethe display panel 8. The driving sequence is previously stored in thepieces of control signal information 6(1) to 6(n) in the mode-by-modecontrol signal generating circuit 5 and is accomplished by performingcontrol to select one of the pieces of control signal information 6(1)to 6(n) in response to the signal format of the input signal.

(H) Color Temperature Conversion

In this preferred embodiment, the processing in the video signalprocessing circuit 3 is changed in response to the signal format of theinput signal.

In many cases, colors of high color temperatures are generally preferredfor the television image. With the PDP, the luminance efficiency of bluephosphors is relatively lower than that of other colors because ofstate-of-the-art process technology and restrictions on the physicalproperties of the phosphors. To raise the color temperature of blue, theluminance of other colors (green and red) among the three primary colorsof light must be lowered. Accordingly, when an image of a high colortemperature is displayed on the PDP, the luminance of the entire PDPtends to decrease, resulting in poor visibility. Thus, some means mustbe devised to display characters and the like.

In this preferred embodiment, the characteristics of the colortemperature conversion in the video signal processing circuit 3 arechanged in response to the type of the input signal. That is, the colortemperature conversion is performed based on the input signal formatupon image data provided by digitizing a net image signal part after theseparation of a synchronization signal part from the input signal. Morespecifically, a higher color temperature is set for the televisionsignal, and a lower color temperature is set for the graphic signal.This provides a high luminance to enable good visibility of charactersand the like when the input signal is the graphic signal. Further, whenthe input signal is the television signal, the color temperature israised to display a generally preferred image.

Additionally, the color temperature may be controlled depending onwhether the television signal is the NTSC signal, the PAL signal, or theSECAM signal. In particular, since lower color temperatures arepreferred in Europe, the color temperatures for the PAL and SECAMsignals adopted in Europe may be set slightly lower than those for theNTSC signal.

While the invention has been described in detail, the foregoingdescription is in all aspects illustrative and not restrictive. It isunderstood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

I claim:
 1. A plasma display device comprising: a plasma display panelin which a plurality of discharge cells are formed; a panel drivecontrolling whether or not luminescence is caused on each of saidplurality of discharge cells by applying to said plasma display panel, adrive pulse including priming pulses which cause priming discharges insaid plurality of discharge cells and sustain pulses which causeluminescence on said plurality of discharge cells; a video signalprocessor converting a video signal as inputted to digital image data tobe displayed; and a control signal generating circuit for controllingoccurrences of said drive pulse which is caused by said panel drive inaccordance with a signal format of said video signal as inputted, thesignal format being identified by a signal format identifier prior tobeing provided to said control signal generating circuit.
 2. The plasmadisplay device according to claim 1, wherein said control signalgenerating circuit controls a number of subfields time periods obtainedby dividing a time period of one field into a plurality of time periods,to control a number of gradations on a display of said plasma displaypanel, in accordance with said signal format of said video signal. 3.The plasma display device according to claim 2, wherein said controlsignal generating circuit controls whether or not a number of subfieldstime periods obtained by dividing a time period of one field into aplurality of time periods exceeds a minimum number required to representeach of said gradations which is determined in accordance with saidsignal format of said video signal, in accordance with said signalformat of said video signal.
 4. The plasma display device according toclaim 1, wherein said control signal generating circuit controls anumber of said priming pulses per field, in accordance with said signalformat of said video signal.
 5. The plasma display device according toclaim 1, wherein said control signal generating circuit varies a timeperiod set for writing data to supply said wall charge to said pluralityof discharge cells, in accordance with said signal format of said videosignal.
 6. The plasma display device according to claim 1, wherein saidcontrol signal generating circuit controls automatic power controlcharacteristics, in accordance with said signal format of said videosignal.
 7. The plasma display device according to claim 1, wherein saidcontrol signal generating circuit varies a number of said sustain pulsesper field so as to be inversely proportional to a verticalsynchronization frequency of said video signal, in accordance with saidsignal format of said video signal.
 8. The plasma display deviceaccording to claim 1, wherein said video signal processor variescharacteristics of color temperature conversion performed on said imagedata, in accordance with said signal format of said video signal.